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Description: One direction of 19.37 from the same axioms as 19.37imv . (Contributed by BJ, 2-Dec-2023)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-19.37im | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ∃ 𝑥 ( 𝜑 → 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 19.35 | ⊢ ( ∃ 𝑥 ( 𝜑 → 𝜓 ) ↔ ( ∀ 𝑥 𝜑 → ∃ 𝑥 𝜓 ) ) | |
| 2 | bj-nnfa | ⊢ ( Ⅎ' 𝑥 𝜑 → ( 𝜑 → ∀ 𝑥 𝜑 ) ) | |
| 3 | 2 | imim1d | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ( ∀ 𝑥 𝜑 → ∃ 𝑥 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |
| 4 | 1 3 | biimtrid | ⊢ ( Ⅎ' 𝑥 𝜑 → ( ∃ 𝑥 ( 𝜑 → 𝜓 ) → ( 𝜑 → ∃ 𝑥 𝜓 ) ) ) |